Screw-cutting device.



PATENTED AUG. 25, 1903.. E. W. BULLARD. SGREW CUTTING DEVICE.

APPLICATION F ILED MAY 19, 1903.

N0 MODEL.

.vices, and particularly to improvements in EDWIN w. BULLARD, 0F SPRINGFIELD,MASSACHUSETTS};

UNITED rammed August 25,1903.

PATENT OFFICE.

LISQBEW-CUTTING avies} J SPECIFICATION formingpart of Lettefs iatent Nbi ,737,2o4,= dated August 25, 1903.

. qhpplicationfiledMay19,103. Serial naisvlsagvs (Nomodehl I To all tuhontit may concern:

Beit known that I, EDWIN W. BULLARD, a

citizen of the United States, residi n ar Spring; fiel d, in the county trnampde "and State of Massachusetts, have invented new and useful Improvements in Screw-Quttin'g Deyi I p plate hasl'a central perforation therein, as

of whichthe :following is aspecification.

This inventio'n'relates'to screw-cutting detools of this class in which the dies are constructed to open automatically when the screw has been threaded, thereby obviating the necessity of reversing the rotation of the tool or the work to withdraw the latter.

The particular object of this invention is to provide improved means to efiect the opening and closing of the dies and to improvements in the construction of the device,whereby it is adapted to be operated either by the endwise movement of the tool, as in a certain and pointed out thereof.

In the drawings forming part of this specification, Figure 1 is a sectional elevation of a screw-cutting device embodying the inven' tion. Fig.- 2 is a sectional'el'evation, partly in section, of a portionofthe devices shown in Fig. '1, but'sho'wing different meansrfor Fig. ,3 is a trans: Fig. 4 is a transverse section on line 44,-Fig. 2,

' each lever'n and the cylindrical shell t,which operating these devices. verse section taken on line 33, Fig. 1.

looking to theleft. W

Referring now'to thedrawings, d, Fig. 1,

indicates a portion of the turret; b, a toolholder mounted in the turret and capable of f shown,-to'recei've the "shell 1, which may be sein axial alinement with the tool-holder 1), againstwhich certain parts-ofthe screw-cutting de vice come in contact toeifect the closing of the dies by means which will be fully described radial movement therein. p

' 0 indicates a post secured to the turret farther on.

The screw-cuttingdevice proper consists of a solid cylindrical head (1, having a shank e are held in place in the head by a circular plate 9, whicli 'is screwed to" the; the head by sorews'h, (shownionly, in "Fig. 3 in section,

being understood that the dies f when inf position in'the ead a mayjsnde freely in their --radial slots when the. plate g is screwed down firmly on'the head. "This .shown'and indicated by i, through whichthe work may be introduced to the dies, and in line with 'this opening 5 is'a hole j, bored in the head and extending down into the shank e. A transversely-located perforation it extends through the hole j.

. Extending from the bottom of the radial slots in which the dies f slide are narrower .slots, (ind-icatedbym,) which extend through the'headd,'parallel with the axis thereof, in which 'tliele'vers n are mounted pivotally on pins oka Theupper ends of these levers enter anotch 0 cut 'in'the under side of the dies,

theoppos'i'te end of said levers extending down below tliehead' and along the shank e, gth'e inner edge thereof having two rectangular steps p and q cu't'therein.

, 'Sliding on the shank e is a collar r, whose forward edge may engage the steps p and g on each of the three levers n. When the collar rests on the steps 19, as shown in Fig. 1, the dies f will be moved radially toward the center of the head. When the collar r is drawn bac k on'the shank in position to engage the steps 'q of 'the levers n, then the dies f will be moved radially away from the center of the head, this movement being effected by a spring 8, located between the lower end of iincroses' said levers and the parts of the device ,by'whichthe latter are operated. Preferably the loweredge of the headd is turned down, as

hub-like projection of smallendiameter than said collar, having a tapered forward end, (in dicated by '22,) so located as to slide under the free ends of the levers it when the collar is pushed toward the dies, as by its contact with the post 0, when the tool-holder is retracted, i

and between. this collar it and the collar r is a spiral spring 10, so arranged as to normally press the collar otoward the dies and the collar u in the opposite direction. The movement of the collar q toward the dies is limited by a cross-head 0;, located in the transverse slot 7c in the shank e and passing through the plunger y, located in the holej. WVhen the collar 1* is in its most forward position, the steps 13 of the levers u. will rest on the forward edge thereof.

From the above description it is obvious that the sliding movement of the collaru operates only to move the dies inward, and the movement of this collar will compress the spring 10, and as soon as the tapered end of the collar has swung the inner ends of the levers 92. outward far enough to release the end of the collar 4' from the steps q then the spring 10 will shoot the collar forward into a position of engagement with the notches 1'), thus locking the dies fin a closed position. It now the tool-holder I) be advanced toward the work, the spring "(0, operating in inverse direction on the collar 20, will cause the latter to slide rearwardly, whereby its tapered end may be withdrawn from under the end of the levers n, the springs s holding the levers n firmly against the periphery of the collar 0'. Any suitable stop, as the collar .2, may be used to limit the rearward movement of the collar a. The collar 1' thus serves as a gage to determine the degree to which the dies may be opened. As the dies perform their work on a rod the end of the latter will come in contact with the end of the plunger y, forcing the latter and the collar 0 rearwardly until the forward end of the collar reaches the steps q, whereupon the springs s behind the levers n will operate to throw the ends of the latter inwardly and retract the dies J from the work, this movement of the levers n being permitted by the retirement of the collar to. It is thus seen that the function of the collar It is to reset the dies and the function of the collar 9' to hold the dies in their operative position, the diameter of said collar?" serving as a gage to determine accurately the diameter of the work measured from the bottom of the thread cut thereon. I am aware that it is not broadly new to construct a screw-cutting device having radially-movable dies which are set in operative position by means of a cone operating substantially like that on the collar to, but it is new, so far as I am aware, to construct a device of this character in which there is embodied a member associated with the cone which serves as an accurate gage to determine the diameter of the work and to positively hold the dies upto their work. lVhere the cone performs both of these functions, a very slight variation in the movement of the cone will result in a like variation in the diameter of the finished work, and the operation of such a device is too uncertain to permit of its use in cases where it is necessary that the work should be accurately finished.

111 the foregoing description that type of the screw-cutting device in which the dies are openedv by a longitudinal movement of the device has been described; but, as heretofore explained, the dies may be operated by other mechanism than that just described, consisting of the post 0, and other means for imparting forward movement to the collar u are shown in Figs. 2 and 1', Fig. 2 particularly showing most clearly the modification in the construction of the device whereby endwise motion of the collar is imparted by means of two inclines, (indicated by 2,) which are cut 011 the rear edge of the collar, and pins 3 in the shank c at right angles thereto are so located that if the collar to be rotated the action of these inclined planes on said pins will. force the collar forward toward the dies during its rotativc movement. These inclines start from notches 2, located in opposite sides of the collar to, in which the ends of the pin 3 rest when the collar is in its normal position. To effect this movement, a short arm 4; is socured to the rear of the collar and projects beyond the casing at right angles to the shank e, as shown in said Figs. 2 and el. ()11 the frame of the machine (indicated by 5) a block 6 is located, which lies in the path of revolution of the arm at as the latter moves with the horizontally-revolvin g turret in which the tool is secured. The spring w in this construction is attached by one end to the collar 9' and by its opposite end to the collar it, all as shown in Fig. 2, and this spring therefore will have the double function of serving to actuate the collars q' and u endwise, as above de scribed, and also by its torsional action to retate the collar 16 back to the position shown in Fig. 2 after the rotative movement imparted to said collar, (indicated by the position of the arm 4 in dotted lines in Fig. 4-.) In order to prevent the rotation of the collar 0' on the shaft under the torsional action of the spring w, the cross-head a; on the plunger 1 is let into a groove 7, formed transversely of the forward end of said collar 9'. This will hold the latter against rotation, and thus it will constitute an abutment against which the spring w may be placed under torsional strain by the rotation of the collar 10.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

1. A head having a shank thereon, screwcutting dies located in radially-disposed slots in said head, a lever for each die pivotally mounted on the head, one end of the levers engaging said dies; a collar slidable on the shank to block the swinging movement of said levers in one direction and limit the opening movement of the dies, and a second collar having a tapered end thereon to engage the ends of said levers to move the dies inwardly, together with a spring to normally force said two collars in opposite directions, means actuated by the work to disengage said ii rst-named collar from its lever-blocking position, and means to slide said 'second collar toward the first-named collar. 2. A radially-slotted circular head, dies located in the slots in the head, levers pivoted in the head under the dies and parallel with the axis of the head to engage the dies to move them endwise, the inner edge of said lethe axis of the head toengage the dies tomove them endwise, the inner edge of said dies having steps formed thereon; suitable means to swing the free ends of the levers outwardly consisting of a collar slidable and rotatable on said head, portions of said collar being spirally disposed thereon; an abutment on the head against which said spiral portions may bear, and means to rotate said collar; a separate spring-actuated member adapted to snap under the ends of said levers upon their outward movement to engage one of the steps formed on the latter, whereby the degree of openin g of said dies may be limited, and means actuated by the work to displace said spring-actuated member.

- EDWIN W. BULLARD.

Witnesses:

WM. 11. CHAPIN, K. I. CLEMONS. 

